"Your enemies are in for a big surprise with the Giga Tesla, the foul-tempered big brother of the Tesla family. When an enemy so much as scratches the paint on your Town Hall, sizzling Electrickery will blast them away leaving the air tasting faintly like coconut... and metal."
Town Hall level 12 is the only Town Hall to sport one of these Giga Teslas. A level 1 Giga Tesla is already built-in with the Town Hall when the Town Hall level 12 upgrade is completed.
The Giga Tesla deals very high damage per second to multiple targets at once. It only emerges when the Town Hall is damaged (by troop or spell), or when 51% of the base is destroyed.
When upgraded to level 5, the Giga Tesla, in addition to dealing its normal damage, also doubles as a bomb of sorts, which explodes when the Town Hall is destroyed. This is similar to the Bomb Tower.
The levels of the Giga Tesla are denoted by the number of stars that can be seen when tapping on a Town Hall 12. Roman numerals on the side of the Town Hall also show the level of the Giga Tesla inside.
Strategy and Tips
The Giga Tesla can be extremely dangerous, especially when upgraded to target three or even four troops at a time; it can be compared to a multi-targeting Inferno Tower damage-wise. You can consider using a Freeze Spell on the Giga Tesla to stop it from wreaking havoc on your troops.
Sometimes it is bad for the Giga Tesla to be triggered as then defense-targeting troops (e.g. Giants, Balloons, Golems) can then attack the Town Hall. It is good to have a single-target Inferno Tower nearby to counteract this.
It can be useful to use a single Earthquake Spell to activate the Giga Tesla so that defense-targeting troops such as Balloons can path towards and target the Town Hall. This is often best done when these troops are close to the Town Hall so that the Giga Tesla gets less time to fire upon these troops.
When going against a level 5 Giga Tesla, be prepared for its explosion if you destroy it, as it can easily wipe out many smaller troops, including Bowlers and Balloons, and also significantly hurt your larger troops and Heroes. The Grand Warden's Eternal Tome ability can be useful to prevent the explosion damage from hurting your troops.
The explosion radius, while significant, is smaller than the range of the Giga Tesla. Long-ranged units like the Archer Queen can stay clear of the blast if they do not move towards the Town Hall before it explodes.
If the Town Hall is isolated with a large empty space around it, as is usually the case in anti 2-star bases, it can often be useful to allow a lone Wall Wrecker or Battle Blimp (loaded with high damage Clan Castle troops, such as P.E.K.K.As, Valkyries or Balloons) to target the Town Hall while the rest of the army can be used to clear the buildings around the sides. If you manage to take down the Town Hall with the Siege Machine, the explosion will likely only affect any Clan Castle troops you used to take it down, and you can use the Warden's ability elsewhere (against the Eagle Artillery, for example).
At level 1, a small conductor rod pops out of the trap door on top of the Town Hall.
At level 2, the rod color changes to gold and gains a gold ring around the top of it.
At both levels 3 and 4, the electricity now emits from two rings on each side of the Town Hall.
At level 5, the Giga Tesla gets noticeably bigger as a big round ball of electricity.
The level 5 Giga Tesla represents a bigger version of Hidden Tesla level 10.
It's one of two defenses to do explosive damage when destroyed, the other being the Bomb Tower.
It's one of two defenses to simultaneously target multiple non-adjacent troops, the other being the Inferno Tower in multi-target mode.
Its triggering criteria could be inspired by the Clash Royale King's Tower: either taking damage or certain buildings are destroyed (in Clash Royale's case, a Princess Tower).
Like all other defenses, if the Giga Tesla is under upgrade, it won't defend, and the Town Hall acts like a level 1~11 Town Hall.